You are in: eMedicine Specialties > Neurology > Neurological Infections HIV-1 Associated CNS Complications (Overview)Article Last Updated: Aug 27, 2007AUTHOR AND EDITOR INFORMATIONSection 1 of 8
  Author: Niranjan N Singh, MD, DNB, Fellow in Neurophysiology, Department of Neurology, St Louis University School of Medicine Niranjan N Singh is a member of the following medical societies: American Academy of Neurology Coauthor(s): Florian P Thomas, MD, MA, PhD, Drmed, Director, Spinal Cord Injury Unit, St. Louis VAMC, Associate Program Director, Associate Professor, Departments of Neurology, Molecular Virology, and Molecular Microbiology and Immunology, Saint Louis University School of Medicine; R Charles Callison Jr, MD, Staff Physician, Department of Neurology, St Louis University School of Medicine Editors: William J Nowack, MD, Associate Professor, Department of Neurology, Epilepsy Center, University of Kansas Medical Center; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; Richard J Caselli, MD, Professor, Department of Neurology, Mayo Medical School, Rochester, MN; Chair, Department of Neurology, Mayo Clinic of Scottsdale; Selim R Benbadis, MD, Professor, Director of Comprehensive Epilepsy Program, Departments of Neurology and Neurosurgery, University of South Florida School of Medicine, Tampa General Hospital; Nicholas Y Lorenzo, MD, Chief Editor, eMedicine Neurology; Consulting Staff, Neurology Specialists and Consultants Author and Editor Disclosure Synonyms and related keywords: acquired immunodeficiency syndrome, AIDS, human immunodeficiency virus, HIV infection, HIV-1–associated cognitive/motor complex, AIDS dementia complex, ADC, vacuolar myelopathy, peripheral neuropathies, CNS lymphoma, Kaposi sarcoma, Kaposi's sarcoma, progressive multifocal leukoencephalopathy, PML, cryptococcal meningitis, tuberculous meningitis, cerebrovascular diseases, toxoplasmosis, neurocysticercosis, cytomegalovirus infection, CMV, neurologic complications of HIV, immune reconstitution inflammatory syndrome, IRIS INTRODUCTIONSection 2 of 8
  BackgroundMultiform CNS complications accompany HIV infection. The HIV-1–associated cognitive/motor complex or AIDS dementia complex (ADC), vacuolar myelopathy, and certain peripheral neuropathies are several conditions that may be caused, directly or indirectly, by HIV itself. Conditions caused by infectious, autoimmune, or neoplastic processes secondary to immunodeficiency include CNS lymphoma, Kaposi sarcoma, progressive multifocal leukoencephalopathy (PML), cryptococcal meningitis, tuberculous meningitis, cerebrovascular diseases, some neuropathies and myopathies, toxoplasmosis, neurocysticercosis, and cytomegalovirus (CMV) infection. Some neurologic conditions are caused by antiretroviral drugs. In addition, AIDS patients are susceptible to the same neurologic diseases as patients who do not have HIV infection. In AIDS, a clinical presentation often cannot be explained with a single diagnosis. New-onset neurologic complications often are superimposed on an ongoing process with a different etiology. Clinical features reflect the sum of deficits at several anatomic sites. The manifestations of AIDS and its neurologic complications differ in children, whose immune and nervous systems are infected at an immature stage, whether in utero, during delivery, or postpartum. CNS complications tend to progress more rapidly in children, probably because of the inability of their immune systems to mount an appropriate T-cell, B-cell, or cytokine response to the infection. Neurologic involvement in HIV infection is more frequent in children than in adults. It may take the form of a loss of previously acquired intellectual and motor milestones or of developmental delay. Opportunistic infections due to reactivation of dormant organisms are unusual, as children may not have been exposed yet to the responsible organisms. Distinguishing features include blood vessel calcification in the basal ganglia, large necrotizing cortical and subcortical lesions, microcephaly, and infection of astrocytes. PathophysiologyWhen immune defenses are impaired, opportunistic infections and neoplasms arise, often from reactivation of previously acquired organisms. This mechanism applies to agents such as Toxoplasma gondii and Epstein-Barr virus (EBV). Other organisms, such as the JC or SV40 viruses that cause PML, may be activated directly by HIV gene products. The likelihood of a particular neurologic syndrome correlates with the clinical stage of HIV infection as reflected by viral load, immune response, and CD4+ lymphocyte counts. This, in turn, is related to the severity of immunodeficiency and autoimmunity and to serum and tissue cytokine levels. Manifestations at seroconversion are often subclinical but may include meningitis, acute encephalopathy with seizures, confusion, and delirium. HIV enters the CNS soon after initial infection. Early peripheral nerve manifestations include isolated acute cranial nerve palsies and Guillain-Barré syndrome. Neurologic complications seen in AIDS include ADC, vacuolar myelopathy, opportunistic infections and neoplasms, and chronic neuropathies (usually several years after HIV infection). FrequencyUnited StatesNeurologic complications are present in more than 40% of patients with HIV. They are the presenting feature of AIDS in 10-20%. At autopsy, the prevalence of neuropathologic abnormalities is 80%. Mortality/MorbidityMortality and morbidity rates reflect risks due to both the neurologic condition and severe immunodeficiency. AgeNeurologic complications occur at any age. DIFFERENTIALSSection 3 of 8
Alzheimer Disease Aphasia Cardioembolic Stroke Cavernous Sinus Syndromes Cerebral Venous Thrombosis EEG in Dementia and Encephalopathy Epidural Hematoma Frontal and Temporal Lobe Dementia Frontal Lobe Syndromes Herpes Simplex Encephalitis HIV-1 Associated Cerebrovascular Complications HIV-1 Associated CNS Conditions: Meningitis HIV-1 Associated Opportunistic Infections: CNS Cryptococcosis HIV-1 Associated Opportunistic Infections: CNS Toxoplasmosis HIV-1 Associated Opportunistic Infections: Cytomegalovirus Encephalitis HIV-1 Associated Opportunistic Infections: PML HIV-1 Associated Opportunistic Neoplasms: CNS Lymphoma HIV-1 Associated Vacuolar Myelopathy HIV-1 Encephalopathy and AIDS Dementia Complex Huntington Disease Intracranial Epidural Abscess Intracranial Hemorrhage Lacunar Syndromes Neurocysticercosis Posterior Cerebral Artery Stroke Primary CNS Lymphoma Spinal Cord Hemorrhage Spinal Cord Infarction Spinal Epidural Abscess Subdural Empyema Subdural Hematoma Tuberculous Meningitis Uremic Encephalopathy Vasculitic Neuropathy Viral Encephalitis Viral Meningitis
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